// Minimal event-handling wrapper.
function stopEvent() {
  if (this.preventDefault) {this.preventDefault(); this.stopPropagation();}
  else {this.returnValue = false; this.cancelBubble = true;}
}
function addStop(event) {
  if (!event.stop) event.stop = stopEvent;
  return event;
}
function connect(node, type, handler) {
  function wrapHandler(event) {handler(addStop(event || window.event));}
  if (typeof node.addEventListener == "function")
    node.addEventListener(type, wrapHandler, false);
  else
    node.attachEvent("on" + type, wrapHandler);
}

function forEach(arr, f) {
  for (var i = 0, e = arr.length; i < e; ++i) f(arr[i]);
}

function startTagComplete(editor) {
  // We want a single cursor position.
  if (editor.somethingSelected()) return;
  // Find the token at the cursor
  var cur = editor.getCursor(false), token = editor.getTokenAt(cur), tprop = token;
  // If it's not a 'word-style' token, ignore the token.
  if (!/^[\w$_]*$/.test(token.string)) {
    token = tprop = {start: cur.ch, end: cur.ch, string: "", state: token.state,
                     className: token.string == "." ? "js-property" : null};
  }
  
  // If it is a property, find out what it is a property of.
  while (tprop.className == "js-property") {
    tprop = editor.getTokenAt({line: cur.line, ch: tprop.start});
    if (tprop.string != ".") return;
    tprop = editor.getTokenAt({line: cur.line, ch: tprop.start});
    if (!context) var context = [];
    context.push(tprop);
  }
  
  function insert(str) {
    editor.replaceRange(str, {line: cur.line, ch: token.start}, {line: cur.line, ch: token.end});
  }
  
  insert('<></>');
  editor.focus();
  editor.setCursor({ line: cur.line, ch: token.end });
  return true;
}

function startComplete(editor) {
  // We want a single cursor position.
  if (editor.somethingSelected()) return;
  // Find the token at the cursor
  var cur = editor.getCursor(false), token = editor.getTokenAt(cur), tprop = token;
  // If it's not a 'word-style' token, ignore the token.

  if (token.string == '') return;

  if (!/^[\w$_]*$/.test(token.string)) {
    token = tprop = {start: cur.ch, end: cur.ch, string: "", state: token.state,
                     className: token.string == "." ? "js-property" : null};
  }
  
  // If it is a property, find out what it is a property of.
  while (tprop.className == "js-property") {
    tprop = editor.getTokenAt({line: cur.line, ch: tprop.start});
    if (tprop.string != ".") return;
    tprop = editor.getTokenAt({line: cur.line, ch: tprop.start});
    if (!context) var context = [];
    context.push(tprop);
  }
  
  if (token.string == '' && context === undefined) return;
  
  var completions = getCompletions(token, context, editor);
  if (!completions.length) return;
  function insert(str) {
    editor.replaceRange(str, {line: cur.line, ch: token.start}, {line: cur.line, ch: token.end});
  }
  // When there is only one completion, use it directly.
  if (completions.length == 1) {insert(completions[0]); return true;}

  // Build the select widget
  var complete = document.createElement("div");
  complete.className = "completions";
  var sel = complete.appendChild(document.createElement("select"));
  sel.multiple = true;
  for (var i = 0; i < completions.length; ++i) {
    var opt = sel.appendChild(document.createElement("option"));
    opt.appendChild(document.createTextNode(completions[i]));
  }
  sel.firstChild.selected = true;
  sel.size = Math.min(10, completions.length);
  var pos = editor.cursorCoords();
  complete.style.left = pos.x + "px";
  complete.style.top = pos.yBot + "px";
  complete.style.position = 'absolute';
  complete.style.outline = 'none';
  complete.className = 'autocomplete';
  document.body.appendChild(complete);
  
  // Hack to hide the scrollbar.
  if (completions.length <= 10) {
    complete.style.width = (sel.clientWidth - 1) + "px";
  }

  var done = false;
  function close() {
    if (done) return;
    done = true;
    complete.parentNode.removeChild(complete);
  }
  function pick() {
    insert(sel.options[sel.selectedIndex].value);
    close();
    setTimeout(function(){editor.focus();}, 50);
  }
  
  function pickandclose() {
    pick()
    setTimeout(function () { editor.focus(); }, 50);
  }
  
  connect(sel, "blur", close);
  connect(sel, "keydown", function(event) {
    var code = event.keyCode;
    // Enter and space
    if (code == 13 || code == 32) { event.stop(); pick();}
    // Escape
    else if (code == 27) {event.stop(); close(); editor.focus();}
    else if (code != 38 && code != 40) {close(); editor.focus(); setTimeout(function () { startComplete(editor) }, 50);}
  });
  connect(sel, "dblclick", pick);

  sel.focus();
  // Opera sometimes ignores focusing a freshly created node
  if (window.opera) setTimeout(function(){if (!done) sel.focus();}, 100);
  return true;
}

var stringProps = ("charAt charCodeAt indexOf lastIndexOf substring substr slice trim trimLeft trimRight " +
                   "toUpperCase toLowerCase split concat match replace search").split(" ");
var arrayProps = ("length concat join splice push pop shift unshift slice reverse sort indexOf " +
                  "lastIndexOf every some filter forEach map reduce reduceRight ").split(" ");
var funcProps = "prototype apply call bind".split(" ");
var keywords = ("break case catch continue debugger default delete do else false finally for function " +
                "if in instanceof new null return switch throw true try typeof var void while with").split(" ");

function getCompletions(token, context, editor) {
  var found = [], start = token.string;
  function maybeAdd(str) {
    if (str && str != start && str.indexOf(start) == 0 && found.indexOf(str) === -1) found.push(str);
  }
  function gatherCompletions(obj) {
    if (typeof obj == "string") forEach(stringProps, maybeAdd);
    else if (obj instanceof Array) forEach(arrayProps, maybeAdd);
    else if (obj instanceof Function) forEach(funcProps, maybeAdd);
    for (var name in obj) maybeAdd(name);
  }

  if (context) {
    // If this is a property, see if it belongs to some object we can
    // find in the current environment.
    var obj = context.pop(), base;
    if (obj.className == "js-variable")
      base = window[obj.string];
    else if (obj.className == "js-string")
      base = "";
    else if (obj.className == "js-atom")
      base = 1;
    while (base != null && context.length)
      base = base[context.pop().string];
    if (base != null) gatherCompletions(base);
  }
  else {
    // If not, just look in the window object and any local scope
    // (reading into JS mode internals to get at the local variables)
    for (var v = token.state.localVars; v; v = v.next) maybeAdd(v.name);
    gatherCompletions(window);
    forEach(keywords, maybeAdd);
  }
  
  // also look up symbols in the current document
  var code = editor.getValue().split(/\W/);
  forEach(code, maybeAdd);
  
  return found;
}
